Triode vacuum tube



Jan. 5, 1932.

l. E. MQUROMTSEFF 1,839,926

muons VACUUM TUBE Filed Jan. 7, 1925 Fig. 4.

INVENTOR Ilia E. Mouromfseff tungsten and is, therefore, more rug.mation of the filaments Patented Jan. 5, 1932 UNITED STATES.

PATENT OFFICE ILIA E. IOUBOITSEFI', O1 WILKINSBUBG,

PENNSYLVANIA, ASBIGNOB 'lO WESTING- ,HOUSE ELECTRIC 0: MANUFACTURINGCOMPANY, A CORPORATION OF PENNSYL- VANIA .7

TRIODE VAGUUI TUBE Application filed January 27, 1925. Serial No. 5,078.

.mionic discharge device which is more re sistant to the electrostaticforces which tend to bend and to destroy the filament.

Another object of my invention is to prop duce a self-supportingtungsten filament cathode structure. 7

Another object of my invention is to produce a double, looped filament,cathode in which the loops are so ported at the bights thereof and alsoboun together at another point.

In prior construction of thermionic discharge devices, it has beencustomary to use looped filament cathodes. In devices adapted for thetranslation of high power, it has been found necessary to apply highvoltages to such devices, usually rangin between- 1,000 and 10,0000)!more volts. t certain portions of the operating cycle of the device,this full voltage is impressed between the anode of the device and thefilamentary cathode. Particularly in. the case of thermionic dischargedevices used for rectifiers without an interposed grid structure, doublethis voltage is applied between the anode and cathode at certainportions of the operating cycle. The filamentary cathode is made of edthan would be the case if it were made 0 certain other metals. But insuch devices, the filament is operating at an elevated temperature whichmay be more or less near to its softening point. It is, therefore, morereadily subject to deformation than it would be at lower temperatures.A. particularly high temperature is required in order to obtain as largean electron emission as possible to cause t e device to motion in thedesired manner.

The electrostatic stresses involved under these operating conditionsresult in a deforcathode, which may continue until the ament breaks, or

until it touches'another electrode and shortcircuits the device.

whereby the electrostatic forces impressed upon the filament may bepartially c0mpensated by similar forces acting in an opposite direction.I obtain this partial compensation by a construction in which two loopedfilaments may be crossed at a point between the ends of the filamentsand the bights of the loop and lashed together at the crossing oint.

invention will be apparent from the following description when read inconnection with the accompanying drawings, wherein:

Fi ure 1 is a View in perspective of a form of amentary cathodeconstructed in accordance with my invention,

Fig. 2 is a diagram of a portion of a filament according tomy inventionand indicating the stresses which are ap lied thereto,

Fig. 3 is a diagrammatic etch of the structure, of my invention alsoindicating the nature of the stresses a plied thereto,

Fig. 4 is a view, partia ly in section and partially in elevation, ofa'device embodying a form of my invention, and

Fi 5 is a plan view taken on the line V-- of Fig. 4.

Referring to Fig. 2, there is indicated diagrammaticall a method ofcompensating the electrostatic orces accordin to a form of my inventionwhich consists in positioning a filament diagonally within thecylindrical anode, whereby the resultant forces are in one direction atthe bight ends of the filament and in another direction at the supportend.

Fig. 3 showsa diagrammatic representa two filaments which are boundtogether by Other objects and structural details of my 'tion of thedisposition of the electrostatic so My invention provides a constructionthe members 4 are adjacent the respective l0! ends of the two filamentswhich are connected to the same inleading wires and which, accordingly,have the same polarity. This construction opposes the stresses upon onefilament to those in an opposite direction upon anotherfilament, andthereby reduces the effect thereof upon the filament. The filaments areconnected in parallel to the supply leads, and the distance from thesupport wires to bindi'n wires 4, being the same for each filament, t epotential. drop is the same, and the crossing point is an equipotentialpoint.

In Figs. 1, a and 5 are shown filaments 1 and 2, a spring supportingmember 3, and bindingrmeans 4 consisting of a wrappin of wire,preferably of tungsten. An ano e 5 surrounds the v laments. A vitreousclosure 6 is attached to the anode 5, by aseal 7. Closure 6 hasare-entrant portion 8 and a press triode for various .ing a cathodehavin J thereon through which are passed lead wires 11 and 12. To leadwires 11 and 12 are attached filament support wires 13, 14, 15 and 16 tothe ends of which are attached the ends of filaments 1 and 2. Theportion of my device .sofar described is adapted to be used either as atwo-element rectifier or as a urposes.

If desired, a gri member may be interposed between anode and cathode asshown in lg. 4 at 17. This grid is supported in any desired manner as bylongitu inal wires 18 suitably secured to a supporting band 19, whichsurrounds a glass member 21 sealed to reentrant portion 8 of thecontainer 6. By this means, I am able to produce aself-supporting-cathode structure which is resistant to the deformingefiects of the electrostatic forces of the applied potential.

While I have shown only one embodiment of my invention in theaccompanying drawings, it is capable of various changes andmodifications without de arting from the spirit thereof, and it isesired, therefore, that only such limitations shall be imposed thereonas vare indicated in the prior art or indicated in the appended claims.

I claim-as my invention:

1. A thermionic discharge device compristwo looped filamentselectrically connecte in parallel, a air of elastic supports engagingthe hights t ereof, said filaments cross ng at a point between the endsand bights thereof and electrode means cooperating with said cathode.

2.- A mount for a thermionic discharge device comprising a cathodehaving two loo d filaments connected electrically in paralle a pair ofelastic supports engaging the bights thereof, said filaments crossing ata point be tween the ends and bights thereof, and binding means unitingsaid filaments at said point.

3. A thermionic discharge device comprising in combination an anode, anda cathode comprising a plurality of looped filaments,

lead wires therefor, supporting means for each of said filaments atthree different points, one of said supporting means comprising anelastic hook engaging the bight of said loop, and binding meansattaching said filaments together at equipotential points.

4. A thermionic discharge device including a cathode which comprises two100 ed filaments, each filament being supporte at the three )oints of anisosceles triangle, said filaments lieing so supported with respect toeach other that the plane determined by the three points of sup ort ofone filament intersects the plane (etermined by the three points ofsupport of the other filament on a line between the ends of thefilaments and'the bights thereof, the bases of the said triangles beingsubstantially parallel to each other and electrode means cooperatingwith said cathode.

5. A thermionic discharge device including a cathode which comprises twolooped filaments connected in parallel, each filament being supported atthe three oints of an isosceles triangle, said filaments eing sosupported with respect to each other that the plane determined by thethree points of support of one filament intersects the plane determinedby the three points of support of the other filament on a line betweenthe ends of the filaments and the bi hts thereof the bases of the saidtriangles ing sub stantially parallel to each other and electrode meanscooperating with said cathode.

6. A thermionic discharge device including a cathode which com rises twolooped filaments, the ends of one 'lament being supported by membersspaced apart, the ends of the other filament bein supported by membersspaced apart an s aced awa from said first members, the big t of eachfilament bein on the side of the discharge device whic is opposite theside in which its end supporting members are located and electro e meanscooperating with said cathode.

In testimony whereof, I have hereunto subscribed my name this 21st dayof January,

ILIA E. MOUROMTSEFF.

